Isotopic evidence for nonuniform thinning of lithospheric mantle
... data is converted to information about the depth to the lithosphere - asthenosphere boundary by assuming that tholeiitic basalts sample the mantle at depths less than 50 km, and that alkalic basalts (up to 10% normative nepheline), sample the mantle at depths of 50 to 70 km. These depth ranges, base ...
... data is converted to information about the depth to the lithosphere - asthenosphere boundary by assuming that tholeiitic basalts sample the mantle at depths less than 50 km, and that alkalic basalts (up to 10% normative nepheline), sample the mantle at depths of 50 to 70 km. These depth ranges, base ...
Deformation in the Lower Crust of the San Andreas Fault System in
... Hosgri fault system (17), a potential precursor of the SAF. Plate motions are assumed to be driven primarily through the convective flow in the mantle, but seismicity is observed primarily in the upper crust. Having strength reside mostly in the upper crust is consistent with the limited depth of se ...
... Hosgri fault system (17), a potential precursor of the SAF. Plate motions are assumed to be driven primarily through the convective flow in the mantle, but seismicity is observed primarily in the upper crust. Having strength reside mostly in the upper crust is consistent with the limited depth of se ...
The deep-sea floor ecosystem - School of Ocean and Earth Science
... km2, or approximately 60% of the Earth’s solid surface. It has a number of distinct habitats. These include sediment filled basins, continental slopes and abyssal plains, deep ocean trenches and the exposed pillow basalts of young midocean ridges, seamounts rising 1000 m above the general seafloor, ...
... km2, or approximately 60% of the Earth’s solid surface. It has a number of distinct habitats. These include sediment filled basins, continental slopes and abyssal plains, deep ocean trenches and the exposed pillow basalts of young midocean ridges, seamounts rising 1000 m above the general seafloor, ...
Tiny Bacteria Questions I Big
... and his late nights were more than 1,000 miles off the coast of Panama, in the east Pacific Ocean. McNichol, a biological oceanographer, joined an international team of researchers aboard WHOI’s research vessel Atlantis to study microbes living at some of the most extreme environments on Earth—hydro ...
... and his late nights were more than 1,000 miles off the coast of Panama, in the east Pacific Ocean. McNichol, a biological oceanographer, joined an international team of researchers aboard WHOI’s research vessel Atlantis to study microbes living at some of the most extreme environments on Earth—hydro ...
Asymmetric ocean basins - Indico
... ocean basins mirrors the differences of subduction zones as a function of their geographic ...
... ocean basins mirrors the differences of subduction zones as a function of their geographic ...
Earth Science 16.1 Ocean Circulation
... below promote the growth of microscopic plankton, which in turn support extensive populations of fish and other marine organisms. In the NASA image at right, we see a high chlorophyll concentration along the California coast as a result of phytoplankton growth from the nutrients provided by these up ...
... below promote the growth of microscopic plankton, which in turn support extensive populations of fish and other marine organisms. In the NASA image at right, we see a high chlorophyll concentration along the California coast as a result of phytoplankton growth from the nutrients provided by these up ...
printer-friendly sample test questions
... A. the gravitational force of the Moon has been pulling on Earth’s landmasses forcing them to move. B. the tilt of Earth’s axis has changed several times shifting Earth’s landmasses. C. Earth’s rotation has spun Australia into different locations. D. temperature differences have been creating conve ...
... A. the gravitational force of the Moon has been pulling on Earth’s landmasses forcing them to move. B. the tilt of Earth’s axis has changed several times shifting Earth’s landmasses. C. Earth’s rotation has spun Australia into different locations. D. temperature differences have been creating conve ...
Crustal structure of the ocean-island arc transition at the mid... (Bonin) arc margin Azusa Nishizawa , Kentaro Kaneda
... IOA crust to the SB oceanic crust in their model shows that the crustal thickness decreases from 20 to 6 km within a distance of about 30 km. However, this estimation was based on only two ocean bottom seismographs (OBS) on the SB, and the transition structure was less resoluble. Seafloor topography ...
... IOA crust to the SB oceanic crust in their model shows that the crustal thickness decreases from 20 to 6 km within a distance of about 30 km. However, this estimation was based on only two ocean bottom seismographs (OBS) on the SB, and the transition structure was less resoluble. Seafloor topography ...
Medicines from the Deep - Marine Conservation Biology Institute
... previously unknown to science—cold-water corals as colorful and exotic as their warm-water counterparts, giant sponge reefs up to a mile long and 50 feet high, and a host of exotic creatures adapted to life in the cold, dark depths. The incredible diversity of deep ocean life is linked to the fact t ...
... previously unknown to science—cold-water corals as colorful and exotic as their warm-water counterparts, giant sponge reefs up to a mile long and 50 feet high, and a host of exotic creatures adapted to life in the cold, dark depths. The incredible diversity of deep ocean life is linked to the fact t ...
GEOMAR Highlights | 02
... The opening and closing of ocean gateways in the geologic past has had a huge impact on ocean circulation and thus on climate. The most recent of these events was the shoaling and final closure of the Panama Seaway, which ultimately stopped the flow of relatively fresh Pacific waters via the Caribbe ...
... The opening and closing of ocean gateways in the geologic past has had a huge impact on ocean circulation and thus on climate. The most recent of these events was the shoaling and final closure of the Panama Seaway, which ultimately stopped the flow of relatively fresh Pacific waters via the Caribbe ...
Reconstructing geographical boundary conditions for palaeoclimate
... themes are the subject of ongoing studies and continuous acquisition of new data, either of palaeo-altimetry/bathymetry or from tectonic reconstructions. It is therefore crucial that new relevant insights can be incorporated easily and swiftly into boundary conditions used for palaeoclimate modellin ...
... themes are the subject of ongoing studies and continuous acquisition of new data, either of palaeo-altimetry/bathymetry or from tectonic reconstructions. It is therefore crucial that new relevant insights can be incorporated easily and swiftly into boundary conditions used for palaeoclimate modellin ...
The Puzzling Plates – Part I
... basin, be sure to include it wherever is necessary. The layer of Earth that you have assembled is the upper mantle portion of the lithosphere. The lithosphere is comprised of the upper mantle and the overlying crust. All of the lithosphere is relatively cold rock, as compared to the deeper mantle an ...
... basin, be sure to include it wherever is necessary. The layer of Earth that you have assembled is the upper mantle portion of the lithosphere. The lithosphere is comprised of the upper mantle and the overlying crust. All of the lithosphere is relatively cold rock, as compared to the deeper mantle an ...
Mantle Convection and Structure
... geologic process could enrich or re-enrich the mantle in the incompatible elements removed by melting? The answer is ultimately obvious - you have to introduce melts into the mantle. But how? ...
... geologic process could enrich or re-enrich the mantle in the incompatible elements removed by melting? The answer is ultimately obvious - you have to introduce melts into the mantle. But how? ...
Document
... Lower mantle: 49.2% of Earth's mass; depth of 650-2’890 kilometers The lower mantle contains 72.9% of the mantle-crust mass and is probably composed mainly of silicon, magnesium, and oxygen. It probably also contains some iron, calcium, and aluminum. Scientists make these deductions by assuming the ...
... Lower mantle: 49.2% of Earth's mass; depth of 650-2’890 kilometers The lower mantle contains 72.9% of the mantle-crust mass and is probably composed mainly of silicon, magnesium, and oxygen. It probably also contains some iron, calcium, and aluminum. Scientists make these deductions by assuming the ...
Plate Tectonics: The Unifying Theory
... Features of Mid Ocean Ridges • Central rift valley (width is inversely proportional to the rate of spreading) • Shallow-focus earthquakes • Almost exclusively basalt ...
... Features of Mid Ocean Ridges • Central rift valley (width is inversely proportional to the rate of spreading) • Shallow-focus earthquakes • Almost exclusively basalt ...
Plate tectonics - Free
... The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, which ride on the fluid-like (visco-elastic solid) asthenosphere. Plate motions range up to a typical 10–40 mm/year (MidAtlantic Ridge; about as fast as fingernails grow), to about 160 mm/year ...
... The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, which ride on the fluid-like (visco-elastic solid) asthenosphere. Plate motions range up to a typical 10–40 mm/year (MidAtlantic Ridge; about as fast as fingernails grow), to about 160 mm/year ...
Plate Tectonics: GL209 Prof. John Tarney Lecture 3: Wilson Cycle 1
... the continental shelf of the eastern Atlantic seaboard of North America, projected down to 30 km -- based largely on gravity and magnetic evidence, plus some seismic profiles -- and some extrapolation from land geology based on deep drill holes. The critical point is the huge thicknesses of Mesozoic ...
... the continental shelf of the eastern Atlantic seaboard of North America, projected down to 30 km -- based largely on gravity and magnetic evidence, plus some seismic profiles -- and some extrapolation from land geology based on deep drill holes. The critical point is the huge thicknesses of Mesozoic ...
Definition of a Cenozoic alkaline magmatic
... as well as magma production rates are low compared to areas associated with plumes. Uplift and doming typically associated with mantle plumes are also largely absent. Also, to explain the areal distribution of the volcanism, an unusually large plume would have to underlie the entire southwest Pacifi ...
... as well as magma production rates are low compared to areas associated with plumes. Uplift and doming typically associated with mantle plumes are also largely absent. Also, to explain the areal distribution of the volcanism, an unusually large plume would have to underlie the entire southwest Pacifi ...
Distribution and Feeding Ecology of Bathylagus euryops (Teleostei: Microstomatidae) Along the Northern Mid-Atlantic Ridge From Iceland to the Azores
... constant and very low in the mesopelagic zone and nutrient concentrations are typically high. The bathypelagic zone, however, is apparently too deep for sunlight to play a significant role in the behavior and distributions of organisms (Angel, 1997). Primary production varies greatly in the Atlantic ...
... constant and very low in the mesopelagic zone and nutrient concentrations are typically high. The bathypelagic zone, however, is apparently too deep for sunlight to play a significant role in the behavior and distributions of organisms (Angel, 1997). Primary production varies greatly in the Atlantic ...
On the origin of El Chichón volcano and subduction of
... been proposed to occur along deep faults where oceanic plates bend upon entering into subduction (Peacock, 2001; Ranero et al., 2003) or along transform faults (Omori et al., 2002). Ranero et al. (2003) and Omori et al. (2002) suggest that partial serpentinization of the upper mantle offshore Nicara ...
... been proposed to occur along deep faults where oceanic plates bend upon entering into subduction (Peacock, 2001; Ranero et al., 2003) or along transform faults (Omori et al., 2002). Ranero et al. (2003) and Omori et al. (2002) suggest that partial serpentinization of the upper mantle offshore Nicara ...
The Fate of Subducted Oceanic Crust and the Sources of Intraplate
... based on the trace element ratios Nb/U and Ce/Pb. Similar ratios between MORB and OIB compared to crustal compositions have been taken as evidence that crust can not be recycled into the convecting mantle (e.g. Hofmann 1997) except for the possible exception of in the Indian Ocean mantle. Such logic ...
... based on the trace element ratios Nb/U and Ce/Pb. Similar ratios between MORB and OIB compared to crustal compositions have been taken as evidence that crust can not be recycled into the convecting mantle (e.g. Hofmann 1997) except for the possible exception of in the Indian Ocean mantle. Such logic ...
A, Adam, Relation of mantle conductivity to physical conditions in the
... Fig. 3. Lithospheric thickness for continental regions versus surface heat flow after Chapman and Pollack (1977). Data points are depths to seismic low-velocity zone from the following surface-wave studies: (o) Biswas and Knopoff (1974); (A) Goncz and Cleary (1976); ( ~ Wickens (1971). Solid line is ...
... Fig. 3. Lithospheric thickness for continental regions versus surface heat flow after Chapman and Pollack (1977). Data points are depths to seismic low-velocity zone from the following surface-wave studies: (o) Biswas and Knopoff (1974); (A) Goncz and Cleary (1976); ( ~ Wickens (1971). Solid line is ...
Can a Horizontal Astronomical Driving Force and an
... Subduction is driven by buoyancy forces only, reflecting natural subduction systems. A 100-km-thick high-viscosity plate (oceanic lithosphere) overlies 900 km of lower-density mantle, subdivided into 560 km of low-viscosity upper mantle and 340 km of high-viscosity lower mantle, confined in a threed ...
... Subduction is driven by buoyancy forces only, reflecting natural subduction systems. A 100-km-thick high-viscosity plate (oceanic lithosphere) overlies 900 km of lower-density mantle, subdivided into 560 km of low-viscosity upper mantle and 340 km of high-viscosity lower mantle, confined in a threed ...
plate tectonics - School of Ocean and Earth Science and Technology
... upwellings and downwellings. Near Earth’s surface, rocks tend to move away from upwellings and toward downwellings. These surface motions are manifested on Earth as plate tectonics (see Figure 1). Most planets larger than Earth’s moon are thought to be convecting, but the surface expression of this ...
... upwellings and downwellings. Near Earth’s surface, rocks tend to move away from upwellings and toward downwellings. These surface motions are manifested on Earth as plate tectonics (see Figure 1). Most planets larger than Earth’s moon are thought to be convecting, but the surface expression of this ...
Next Generation Sunshine State Standards Chapter 7
... blocks of continental crust eventually collide and form Earth’s great mountain ranges (Figure 7.1). In short, a revolutionary new model of Earth’s tectonic* processes has emerged. This profound reversal of scientific understanding has been appropriately described as a scientific revolution. The revo ...
... blocks of continental crust eventually collide and form Earth’s great mountain ranges (Figure 7.1). In short, a revolutionary new model of Earth’s tectonic* processes has emerged. This profound reversal of scientific understanding has been appropriately described as a scientific revolution. The revo ...
Abyssal plain
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 m. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins (the other elements being an elevated mid-ocean ridge and flanking abyssal hills). In addition to these elements, active oceanic basins (those that are associated with a moving plate tectonic boundary) also typically include an oceanic trench and a subduction zone.Abyssal plains were not recognized as distinct physiographic features of the sea floor until the late 1940s and, until very recently, none had been studied on a systematic basis. They are poorly preserved in the sedimentary record, because they tend to be consumed by the subduction process. The creation of the abyssal plain is the end result of spreading of the seafloor (plate tectonics) and melting of the lower oceanic crust. Magma rises from above the asthenosphere (a layer of the upper mantle) and as this basaltic material reaches the surface at mid-ocean ridges it forms new oceanic crust. This is constantly pulled sideways by spreading of the seafloor. Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited by turbidity currents that have been channelled from the continental margins along submarine canyons down into deeper water. The remainder of the sediment is composed chiefly of pelagic sediments. Metallic nodules are common in some areas of the plains, with varying concentrations of metals, including manganese, iron, nickel, cobalt, and copper. These nodules may provide a significant resource for future mining ventures.Owing in part to their vast size, abyssal plains are currently believed to be a major reservoir of biodiversity. The abyss also exerts significant influence upon ocean carbon cycling, dissolution of calcium carbonate, and atmospheric CO2 concentrations over timescales of 100–1000 years. The structure and function of abyssal ecosystems are strongly influenced by the rate of flux of food to the seafloor and the composition of the material that settles. Factors such as climate change, fishing practices, and ocean fertilization are expected to have a substantial effect on patterns of primary production in the euphotic zone. This will undoubtedly impact the flux of organic material to the abyss in a similar manner and thus have a profound effect on the structure, function and diversity of abyssal ecosystems.